(function () {

    var C = (typeof window === 'undefined') ? require('./Crypto').Crypto : window.Crypto;

// Shortcuts
    var util = C.util,
        charenc = C.charenc,
        UTF8 = charenc.UTF8,
        Binary = charenc.Binary;

    var MARC4 = C.MARC4 = {

        /**
         * Public API
         */

        encrypt: function (message, password) {

            var

                // Convert to bytes
                m = UTF8.stringToBytes(message),

                // Generate random IV
                iv = util.randomBytes(16),

                // Generate key
                k = password.constructor == String ?
                    // Derive key from passphrase
                    C.PBKDF2(password, iv, 32, {asBytes: true}) :
                    // else, assume byte array representing cryptographic key
                    password;

            // Encrypt
            MARC4._marc4(m, k, 1536);

            // Return ciphertext
            return util.bytesToBase64(iv.concat(m));

        },

        decrypt: function (ciphertext, password) {

            var

                // Convert to bytes
                c = util.base64ToBytes(ciphertext),

                // Separate IV and message
                iv = c.splice(0, 16),

                // Generate key
                k = password.constructor == String ?
                    // Derive key from passphrase
                    C.PBKDF2(password, iv, 32, {asBytes: true}) :
                    // else, assume byte array representing cryptographic key
                    password;

            // Decrypt
            MARC4._marc4(c, k, 1536);

            // Return plaintext
            return UTF8.bytesToString(c);

        },


        /**
         * Internal methods
         */

        // The core
        _marc4: function (m, k, drop) {

            // State variables
            var i, j, s, temp;

            // Key setup
            for (i = 0, s = []; i < 256; i++) s[i] = i;
            for (i = 0, j = 0; i < 256; i++) {

                j = (j + s[i] + k[i % k.length]) % 256;

                // Swap
                temp = s[i];
                s[i] = s[j];
                s[j] = temp;

            }

            // Clear counters
            i = j = 0;

            // Encryption
            for (var k = -drop; k < m.length; k++) {

                i = (i + 1) % 256;
                j = (j + s[i]) % 256;

                // Swap
                temp = s[i];
                s[i] = s[j];
                s[j] = temp;

                // Stop here if we're still dropping keystream
                if (k < 0) continue;

                // Encrypt
                m[k] ^= s[(s[i] + s[j]) % 256];

            }

        }

    };

})();
